An accomplished skater and puckhandler, defenseman Tom Johnson played a valuable role on the powerful Montreal Canadiens teams of the 1950s. He contributed to the Habs' rapid transitional game and would have scored more points had the team not already been blessed with Doug Harvey to quarterback the power-play. One of his key traits was an ability to recover almost immediately after making a rare mistake on the ice.

In his first year of junior with the Winnipeg Monarchs in 1946-47, Johnson was deemed to have too many rough edges to be worthy of a spot on the Toronto Maple Leafs' list of 18 sponsored players. Following a match in which he scored the tying and winning goal on end-to-end rushes, a Montreal Canadiens' scout worked out a cash settlement with the Leafs and placed him on their negotiation list.

The first year Johnson came to Montreal, general manager Frank Selke was unable to gain a transfer from the Canadian Amateur Hockey Association. The young blueliner spent a year playing informal hockey, taking a few classes at McGill University and spending valuable time around the Habs' winning environment at the Forum. Beginning the next year, he made two brief appearances with the big club but spent the majority of his first three pro seasons refining his game with the Montreal Royals of the Quebec Senior League and then the Buffalo Bisons of the AHL. In the minors he impressed coaches both with his enthusiasm from the bench and his work ethic on the ice. He also improved his skating, which had always been his one major drawback.

Johnson stepped into a starting role with the Habs in 1950-1951 and impressed them with his eagerness and durability in playing all 70 regular-season games. He was, however, vulnerable to common rookie mistakes such as hasty decision-making and taking unwise penalties. Johnson soon became a stalwart on the penalty-killing unit, where the team utilized his speed and his ability to win the majority of the battles in the corners. One of Johnson's patented moves was to steal the puck from an attacking forward without bodily contact. This allowed him to feed a pass to one of his teammates while the opposition was still heading toward the Montreal net.
Although Johnson rarely saw power-play duty, coach Dick Irvin often switched him to center if the Habs needed a goal late in the game. Johnson won his first Stanley Cup ring in 1953 when the Habs defeated Boston. He later played a vital role on the Canadiens squad that won the Stanley Cup an unprecedented five consecutive times from 1956 to 1960.

By the time the team began dominating the NHL, Johnson was beginning to receive his due credit. In 1956 he was selected to the NHL Second All-Star Team. Three years later, he won the Norris Trophy and earned a spot on the First All-Star lineup. That year he was arguably the most valuable player on the team as he stepped into the void created when Doug Harvey was injured. Johnson didn't have Harvey's speed but he was a superb stickhandler and a consistent, accurate passer who rarely erred in his own end of the rink.

Johnson remained a key veteran following the glory years. During the early 1960s, he often formed an effective partnership with young Jacques Laperriere. Johnson's fortunes took a turn for the worse in 1962-63 when he suffered a horrific facial injury that damaged his eye muscles to the point that his career was in jeopardy. In a difficult business decision, the Canadiens left him unprotected in the Waiver Draft since it was unclear whether he could fully recover his vision. Boston took a chance and claimed him, a decision that would quickly help improve their fortunes, which had sagged in recent years.

The burly Johnson played 121 games in Beantown before a skate severed the nerves in his leg and forced him to the sidelines permanently. His 51 goals, 264 points and six Stanley Cup rings spoke loudest for his contribution to the game. Many observers claimed that Johnson rode on the back of Doug Harvey. This analysis proved to be unfair, as he more than held his own on the Habs' back line and often stayed back to cover possible counterattacks when Harvey rushed with the puck. Virtually every defenseman in NHL history would have benefited from a pairing with the legendary number 2.

After retiring, Johnson accepted a position in the Boston front office as assistant to the president and general manager, where he helped Harry Sinden build a team that would eventually win the Stanley Cup in 1970 and 1972. Johnson coached the first of these championship squads and was the assistant general manager of the second. He was elected to the Hockey Hall of Fame in 1970.